Isopollen maps and principal components analysis of Finnish pollen data for 4000, 6000, and 8000 years ago

Isopollen maps of Betula, Pinus, Alnus, Corylus , and Ulmus for 4000, 6000, and 8000 B.P. and of Picea, Tilia , and Quercus for 4000 and 6000 U.P. are presented for Finland. The maps show the major geographical patterns in pollen composition for these three time intervals. Principal components analysis is used as a means of detecting the major gradients in the data. Over 50% of the total variance in the data for each of the three time intervals can he related to major geographical patterns. These patterns emphasize the distinction in pollen composition between southernmost Finland, central Finland, and the extreme north. Changes in the position of the ecotonal boundaries between these areas with time are discussed on the basis of the numerical analyses.